Safety monitoring for cables transmitting data and power

ABSTRACT

In one embodiment, a method generally comprises monitoring real-time electrical data for Power Sourcing Equipment (PSE) transmitting power over a cable to a Powered Device (PD), and identifying changes in the real-time electrical data indicating strain on one or more wires in the cable due to stretching in the one or more wires.

STATEMENT OF RELATED APPLICATIONS

The present application is a continuation-in-part of U.S. patentapplication Ser. No. 15/604,344, entitled THERMAL MODELING FOR CABLESTRANSMITTING DATA AND POWER, filed on May 24, 2017. This application isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to communications networks, andmore particularly, to safety monitoring for cables transmitting data andpower.

BACKGROUND

Communications cables that are used to deliver higher power mayencounter self-heating and variation due to a combination of currentscarried in the cables, how the cables are installed (e.g., cablebundling, horizontal or vertical direction), and what type of cables areused.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an example of a network in which embodimentsdescribed herein may be implemented.

FIG. 1B is a schematic illustrating a simplified example of cableinstallation in a network.

FIG. 2 depicts an example of a network device useful in implementingembodiments described herein.

FIG. 3A is a flowchart illustrating an overview of a process for thermalmodeling of cables, in accordance with one embodiment.

FIG. 3B is a flowchart illustrating details of a process for safetymonitoring of cables, in accordance with one embodiment.

FIG. 4 illustrates detection of cable adjacencies, in accordance withone embodiment.

FIG. 5 illustrates detection of cable adjacencies, in accordance withanother embodiment.

FIG. 6A illustrates use of a TDR (Time Domain Reflectometer) todetermine cable length and health, in accordance with one embodiment.

FIG. 6B is a graph illustrating use of the TDR to indicate stretching inthe cable.

FIG. 6C illustrates a system for measuring a high frequency signal tomonitor stretching in the cable.

FIG. 7 illustrates an example of a risk assessment table providing cablethermal status, in accordance with one embodiment.

FIG. 8 illustrates an example of a risk assessment table providing cablethermal status, in accordance with another embodiment.

FIG. 9 illustrates an example of a risk assessment table providing cablethermal status, in accordance with another embodiment.

FIG. 10 illustrates a graphical view providing risk assessment and cablethermal status, in accordance with one embodiment.

FIG. 11 is a schematic illustrating voltage and current for multi-phasepulse power, in accordance with one embodiment.

FIG. 12 illustrates an example of a risk assessment table providingthermal status for a higher power system operation, in accordance withone embodiment.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

In one embodiment, a method generally comprises monitoring real-timeelectrical data for Power Sourcing Equipment (PSE) transmitting powerover a cable to a Powered Device (PD), and identifying changes in thereal-time electrical data indicating strain on one or more wires in thecable due to stretching in the wires.

In one or more embodiments, a time domain reflectometer is used toidentify variations in impedance over a length of the cable to indicatethe stretching in the wires.

In one or more embodiments, the stretching comprises a localizedreduction in diameter of the wires over time along a vertical portion ofthe cable.

In one or more embodiments, the real-time electrical data is used tocalculate thermal characteristics for the cable and the method furthercomprises periodically updating the thermal characteristics based on themonitored data.

In one or more embodiments, the power comprises multi-phase pulse powerand the monitored data comprises voltage and current for each phase.

In one or more embodiments, the method further comprises identifying awire gauge of the cable based on the data.

In one or more embodiments, the method further comprises measuring cablelength using a time domain reflectometer, wherein the cable length isused to calculate a wire gauge.

In one or more embodiments, the method further comprises detecting anadjacent cable by measuring cross-talk between wires in the cables.

In one or more embodiments, the power comprises pulse power andcross-talk is measured during a transition of a pulse of the pulsepower.

In one or more embodiments, the method further comprises measuring ahigh frequency signal at a receiver at the PD to indicate the stretchingwithin.

In one or more embodiments, the method further comprises identifying athermal rise at the cable and limiting power output at a port of the PSEconnected to the cable.

In one or more embodiments, the method further comprises identifying apercentage of stretch over a specified threshold and limiting poweroutput at a port of the PSE connected to the cable.

In one or more embodiments, the method further comprises identifying apercentage of stretch over a specified threshold level and sending anotification.

In another embodiment, a method generally comprises monitoring real-timeelectrical data at Power Sourcing Equipment (PSE) transmitting powerover a cable to a Powered Device (PD), calculating thermalcharacteristics for the cable based on the monitored data, andperiodically updating the thermal characteristics based on the monitoreddata. The power comprises multi-phase pulse power, the data comprisesvoltage and current measured for each phase of the multi-phase pulsepower, and the voltage is greater than 60 volts at the PSE.

In yet another embodiment, a method comprises monitoring real-timeelectrical data at Power Sourcing Equipment (PSE) transmitting powerover a cable to a Powered Device (PD), wherein the power comprises pulsepower, monitoring cross-talk between wires within the cable and anadjacent cable to identify cable adjacency, performing thermal modelingon the cable, and calculating a thermal rise on the cable based at leastin part on the identified cable adjacency.

Further understanding of the features and advantages of the embodimentsdescribed herein may be realized by reference to the remaining portionsof the specification and the attached drawings.

EXAMPLE EMBODIMENTS

The following description is presented to enable one of ordinary skillin the art to make and use the embodiments. Descriptions of specificembodiments and applications are provided only as examples, and variousmodifications will be readily apparent to those skilled in the art. Thegeneral principles described herein may be applied to other applicationswithout departing from the scope of the embodiments. Thus, theembodiments are not to be limited to those shown, but are to be accordedthe widest scope consistent with the principles and features describedherein. For purpose of clarity, details relating to technical materialthat is known in the technical fields related to the embodiments havenot been described in detail.

In systems used to simultaneously transmit power and data communications(e.g., Power over Ethernet (PoE), Power over Fiber (PoF), higher powerPoE, Extended Safe Power (ESP), and the like), cable heating may degradethe reliability of the communications signals that are carried over thecables and damage the cable plant. Cable plant damage is often a directresult of thermal stress occurring in unattended or non-visiblelocations. In some cases, powered devices may still operate on athermally stressed cable with uncertain operation, thereby leaving auser confused as to how to debug the system. High temperatures may alsolead to higher power costs due to more power dissipated in the cables.In conventional systems, visible inspection may be needed to comply withstandards (e.g., NEC (National Electrical Code), IEEE (Institute ofElectrical and Electronics Engineers) 802.3) and determine theoperational ability of the cable plant between the power sourceequipment and the powered devices. Many instances of failure may bemissed or ignored. As PoE standards allow for higher powertransmissions, temperature concerns are expected to become moreprevalent.

The embodiments described herein provide safety monitoring of cablesthat are used to carry data and power simultaneously. As described indetail below, safety monitoring may include thermal modeling of cablesand monitoring of cables for degradation or variation due to strain onwires (e.g., stretching in vertical installations). Real-time electricalmeasurements provide an accurate and up-to-date analysis of a cableplant health assessment. The embodiments may be used, for example, toidentify power and thermal impact due to self-heating and provide alertsfor possible over heat conditions. One or more embodiments may be usedto limit power output based on the modeling or prevent modes that mayresult in unwanted cable behavior such as heat damage to the cable orother unintended consequences. As described in detail below, one or moreembodiments may collect cable heating factors (e.g., current carried incable, cable type, cable installation, etc.) and use this data to modelexpected temperature rises and other health assessment characteristicsin the cables to determine if the cable can handle the power level andif the integrity of the data carried across the cable is at risk.

In one or more embodiments, the cables may deliver power at a powerlevel higher than used in conventional PoE. For example, power may bedelivered at a power level greater than 100 W and in some cases greaterthan 1000 W. In one or more embodiments, power may be delivered as pulsepower. The term “pulse power” as used herein refers to power that isdelivered in a sequence of pulses in which the voltage varies between avery small voltage (e.g., close to 0V (volts), 3V) during a pulse offinterval and a larger voltage (e.g., ≥12V, ≥24V) during a pulse oninterval. High voltage pulse power (e.g., >56V, ≥60V, ≥300V) may betransmitted from power sourcing equipment (PSE) to a powered device (PD)for use in powering the powered device, as described, for example, inU.S. patent application Ser. No. 16/671,508, (“Initialization andSynchronization for Pulse Power in a Network System”), filed Nov. 1,2019, which is incorporated herein by reference in its entirety.

In one or more embodiments, the pulse power may be transmitted inmultiple phases in a multi-phase pulse power system. For example, one ormore embodiments may use multiple phase (multi-phase) pulse power toachieve less loss, with continuous uninterrupted power to the outputwith overlapping phase pulses to a powered device, as described in U.S.patent application Ser. No. 16/380,954 (“Multiple Phase Pulse Power in aNetwork Communications System”), filed Apr. 10, 2019, which isincorporated herein by reference in its entirety. As described in detailbelow, multiple phases of voltage pulses may be delivered over amulti-phase cable with the pulses in each phase offset from pulses inother phases. Multiple pair cabling may be used, for example, with a DCpulse on each pair, timed in such a manner as to provide approximately100% net duty cycle continuous power at the powered device (or load).

Referring now to the drawings, and first to FIG. 1A, an example of anetwork in which embodiments described herein may be implemented isshown. The embodiments operate in the context of a data communicationsnetwork including multiple network devices. The network may include anynumber of network devices in communication via any number of nodes(e.g., routers, switches, gateways, controllers, or other networkdevices), which facilitate passage of data within the network. Thenetwork devices may communicate over or be in communication with one ormore networks (e.g., local area network (LAN), metropolitan area network(MAN), wide area network (WAN), virtual private network (VPN) (e.g.,Ethernet virtual private network (EVPN), layer 2 virtual private network(L2VPN)), virtual local area network (VLAN), enterprise network,corporate network, data center, Internet, intranet, or any othernetwork).

The network may be configured for Power over Ethernet (PoE), Power overFiber (PoF), advanced power over data, ESP (Extended Safe Power) (e.g.,delivery of pulse power with fault detection and safety protection),multi-phase pulse power, or any other power over communications cablesystem that is used to pass electric power along with data to allow asingle cable to provide both data connectivity and electric power tonetwork devices such as wireless access points, IP (Internet Protocol)cameras, VoIP (Voice over IP) phones, video cameras, point-of-saledevices, security access control devices, residential devices, buildingautomation, industrial automation, and many other devices. In one ormore embodiments, signals may be exchanged among communicationsequipment and power transmitted from power sourcing equipment to powereddevices. The power may be transmitted in a network system (e.g., networkcommunications system) with or without communications. In one or moreembodiments, the network is configured to transmit pulse power over thecable.

As shown in the simplified example of FIG. 1A, the network may include aPower Sourcing Equipment device (PSE) 10 in communication with anynumber of Powered Devices (PDs) 12 via cables 14. The PSE may be anetwork device such as a router, switch, or central hub that provides(sources) power on the cable 14. The PSE 10 may be configured todelivery power at one or more output levels (e.g., programmable PoE).The network may include any number of PSEs 10 in communication with anynumber of PDs 12. The PD 12 is powered by the PSE 10 and consumesenergy. The PD 12 may be any network device powered by the powertransmitted by the PSE. The PD 12 may be, for example, a switch, router,IP device, or any other device and may be configured to operate at oneor more power levels. The network device may also operate as both a PDand PSE, as described below with respect to FIG. 1B.

The cables 14 are configured to transmit both power and data from thePSE 10 to the PDs 12 (FIG. 1A). The cables 14 may be formed from anymaterial suitable to carry both power and data (e.g., copper, fiber).The cable may include any number of wires or wire pairs. For example,the cable may include a single wire pair (single twisted pair, singlebalanced copper wire pair, single wire pair Ethernet) located in asingle pair cable (e.g., SPE, Base-T1 Ethernet) or any number of wirepairs located in a multi-pair cable (e.g., two-pair cable, four-paircable, Base-T Ethernet). The multi-pair cable may comprise multipleinstances of single wire pairs (e.g., SPE, PoDL) in parallel or multiplewire pairs connected between a pair center tap (e.g., PoE), or any otherconfiguration including high power configurations (e.g., ESP). Thecables 14 may comprise, for example Catx cable (e.g., category 5,category 5e, category 6, etc.) and may be twisted pair (e.g., four pair,SPE (Single Pair Ethernet)) Ethernet cabling, or any other type ofcable.

The cables 14 may extend between the PSE 10 and PDs 12 at a distance,for example, of 10 meters, 100 meters, or any other length. The cables14 may be arranged in any configuration. For example, the cables 14 maybe bundled together in one or more groups 13 or stacked in one or moregroups 15 as shown schematically in cross-section in FIG. 1A. Any numberof cables 14 may be bundled together. The cables 14 may have a round,flat, oval, or any other cross-sectional shape and may include anynumber or type of conductors (e.g., solid or stranded wires). The cables14 may be bundled together at one location 16 while not bundled togetherat another location 17, for example.

The cable 14 may be rated for one or more power levels, a maximum powerlevel, a maximum temperature, or identified according to one or morecategories indicating acceptable power level usage, for example. In oneexample, the cables 14 correspond to a standardized wire gauge systemsuch as AWG (American Wire Gauge). For different gauge wire, AWGprovides data including diameter, area, resistance per length, ampacity(maximum amount of current a conductor can carry before sustainingimmediate or progressive deterioration), and fusing current (how muchcurrent it takes to melt a wire in free air). Various other standards(e.g., NEC (National Electrical Code), UL (Underwriters Laboratories))may be used to provide various requirements for the cable and cablesystem and provide temperature ratings or limits, or other information.This data may be stored in a thermal modeling system for reference inproviding a cable thermal status, as described below.

As noted above, the cables 14 may encounter self-heating. For example,when power is added to twisted-pair cables, the copper conductorsgenerate heat and temperatures rise. A thermal modeling module 18 isconfigured to model the thermal impact due to self-heating. In one ormore embodiments, the thermal modeling module 18 is located at a networkdevice 19, which may be located at a Network Operations Center (NOC),for example. The network device 19 may comprise, for example, a networkmanagement station, controller, computer, or any other device. Thenetwork device 19 is in communication with the PSE 10 and may alsocommunicate with one or more PDs 12 directly or through the PSE. Thethermal modeling module 18 (e.g., code, software, logic, firmware,application, client, appliance, hardware, device, element) may also bedistributed across any number of network devices or operate in a cloudenvironment. Also, the thermal modeling module 18 or one or morecomponents of the module may be located at the PSE 10, as shown in FIG.1A.

The PSE 10 may measure one or more variables used for thermal modelingcalculations at the PSE or at the network device 19. For example, thePSE 10 may measure cable length using a TDR (Time Domain Reflectometer),output voltage at PSE, and current (e.g., for individual conductors). Inone or more embodiments, the PSE 10 may also collect intelligent PDavailable statistics for reporting input voltage at the PD. One or morecalculations may be made at the PSE 10 or at the remote network device19 based on measurements made at the PSE.

The thermal modeling module 18 may collect data including, for example,cable AWG, real-time current carried in the conductors of the cables(nominal or maximum current), voltage (output at PSE, input at PD),cable length, cable segment length, number of PSE ports, cable proximityto other cables carrying currents that can act as localized heatsources, maximum expected ambient temperature where cables are routed,maximum temperature rating of the cable, temperature at PD, or anycombination of this data or other data. Various measurements may be usedto gather real-time data and user input may also be provided for one ormore parameters (e.g., cable type, cable installation configuration,number of ports) if not available. The thermal modeling module 18 mayuse this data to determine the operational maximum power (maximum safeavailable power for delivery on the PSE port), thermal characteristics(real-time temperature rise in cables), overall health of an end-to-endcable 14, a bundle of those end-to-end cables, and a bundle encompassingbundles of cable bundles, and if a cable is safe for operation by theattached PD 12.

As described in detail below, the cable modeling module 18 may calculatereal-time localized heating in a cable plant and generate a cable plantrisk assessment (e.g., spreadsheet, graphical image) and alarm states tominimize unsafe operation. In one or more embodiments, the cablemodeling module 18 may provide an alarm state or syslog (system log)message, as well as prevent delivery of more power than is safelydetermined for a particular cable. For example, the cable modelingmodule 18 may warn a user of potential heating issues and power concernsthat may compromise the cable plant, data integrity of thecommunications channel, and PD operation.

In one or more embodiments, the network device 19 may include a GUI(Graphical User Interface) 11 for receiving user input and presentingresults of the thermal modeling to the user. As described below, the GUI11 may be used to display a risk assessment table or graphical imageindicating the thermal rise, health status, or other information aboutthe cables and cable plant.

FIG. 1B is a simplified schematic illustrating an example of cablerouting in a network. As shown in FIG. 1B, a network device (e.g.,switch) 12 a may operate as a PD and PSE, receiving power from a PSE(e.g., router 10) and transmitting power to one or more PDs or endpoints12 b, 12 c. In the example shown in FIG. 1B, the PSE 10 transmits powerover cable 14 a, 14 b to a switch 12 a, which transmits conventional PoEover cable 14 c and ESP (e.g., multi-phase pulse power) over cable 14 d.In this example, the cable between network devices 10 and 12 a comprisesa vertical section 14 a and a horizontal section 14 b. Cables that runvertically may be susceptible to stretching overtime due to the weightof the cable. For example, the cable (one or more conductors or twistedpairs within cable) may start out with vertical length x1 and over timedue to the weight of the cable may increase to vertical length x2. Theremay be localized thinning of the wire 21 as shown at D2 (reduceddiameter as compared to D1), for example. As described in detail below,TDR may be used to monitor and detect an area of thinning (stretch ofwire 21). For example, impedance at a given point or range in the wire21 may begin to increase as the wire gets thinner, while an impedancepoint or range at another section of the wire may begin to decrease asthe wire gets thicker. In another example, impedance changes may beidentified on the wire 21 given that the source voltage and current, aswell as the load voltage and current remain the same. Over time, withall other variables static, the stretching will become apparent. Asdescribed below, the stretching may be monitored and identified, and ifdegradation of the wire due to stretching increases over a specifiedthreshold, a safety notification or alert may be generated. Thestretching may also be used in the thermal modeling (e.g., lowering anacceptable thermal rise increase on the stretched wire). It is to beunderstood that the cable descriptions herein with respect to the cable14 of FIG. 1A also apply to the cables 14 a, 14 b, 14 c, 14 d shown inFIG. 1B.

It is to be understood that the network devices and topology shown inFIGS. 1A and 1B, and described above are only examples and theembodiments described herein may be implemented in networks comprisingdifferent network topologies or network devices, or using differentprotocols or cables, without departing from the scope of theembodiments. For example, the network may comprise any number or type ofnetwork devices that facilitate passage of data over the network (e.g.,routers, switches, gateways, controllers), network elements that operateas endpoints or hosts (e.g., servers, virtual machines, clients), andany number of network sites or domains in communication with any numberof networks. Thus, network nodes may be used in any suitable networktopology, which may include any number of servers, virtual machines,switches, routers, or other nodes interconnected to form a large andcomplex network, which may include cloud or fog computing. Nodes may becoupled to other nodes or networks through one or more interfacesemploying any suitable wired or wireless connection, which provides aviable pathway for electronic communications.

FIG. 2 illustrates an example of a network device 20 that may be used toimplement the embodiments described herein. In one embodiment, thenetwork device 20 is a programmable machine that may be implemented inhardware, software, or any combination thereof. The network device 20includes one or more processors 22, memory 24, network interface (port)26, and cable modeling module 28.

Memory 24 may be a volatile memory or non-volatile storage, which storesvarious applications, operating systems, modules, and data for executionand use by the processor 22. For example, components of the cablemodeling module 28 (e.g., code, logic, firmware, etc.) may be stored inthe memory 24. Memory 24 may also store manually input data andmonitored data or thermal calculations 25 (e.g., wire gauges andassociated cable temperature ratings, measurements, calculated data, orother data, tables, or graphs). The network device 20 may include anynumber of memory components.

Logic may be encoded in one or more tangible media for execution by theprocessor 22. For example, the processor 22 may execute codes stored ina computer-readable medium such as memory 24. The computer-readablemedium may be, for example, electronic (e.g., RAM (random accessmemory), ROM (read-only memory), EPROM (erasable programmable read-onlymemory)), magnetic, optical (e.g., CD, DVD), electromagnetic,semiconductor technology, or any other suitable medium. In one example,the computer-readable medium comprises a non-transitorycomputer-readable medium. Logic may be used to perform one or morefunctions described below with respect to the flowchart of FIGS. 3A and3B. The network device 20 may include any number of processors 22.

The network interface 26 may comprise any number of interfaces(linecards, ports) for receiving data or transmitting data to otherdevices. The interface may be, for example, an interface at the PSE 10for transmitting power and data to the PD 12, an interface at the PSEfor transmitting measurements, data, or risk assessment information tothe network device 19, or an internal interface at the PSE 10 fortransmitting data to the thermal modeling module 18 (FIGS. 1A and 2).The network interface 26 may include, for example, an Ethernet interfacefor connection to a computer or network. The interface 26 may beconfigured for PoE, PoF, ESP, or similar operation.

It is to be understood that the network device 20 shown in FIG. 2 anddescribed above is only an example and that different configurations ofnetwork devices may be used. For example, the network device 20 mayfurther include any suitable combination of hardware, software,algorithms, processors, devices, components, or elements operable tofacilitate the capabilities described herein.

FIG. 3A is a flowchart illustrating an overview of a process formodeling thermal characteristics of cables used to transmit power anddata, in accordance with one embodiment. At step 30, the thermalmodeling module 18 receives real-time electrical data (e.g., real-timemeasurements of relevant parameters) from the PSE 10 (FIGS. 1A and 3A).In one embodiment, data is extracted from the PSE 10, which may includedata from the PDs 12. User input may be received if an intelligent PD isnot available. The thermal modeling module 18 identifies cableadjacencies and characteristics (step 31). In one embodiment, the PSE 10may use a TDR to determine the cable length at each port. The thermalmodeling module 18 may use voltage, current, and cable length todetermine wire gauge using a calculated resistance. If the PD 12 is notable to provide V_in (voltage at PD), the wire gauge may be provided byuser input. As described below, cable adjacencies (e.g., arrangement ofcables within a bundle, bundle size) may be identified by transmitting apulse at the PSE 10 and then measuring an E field (pulsed fieldstrength) at surrounding cables 14 to detect adjacent cables. Thethermal modeling module 18 may use the wire gauge data, cableadjacencies, and current, voltage, and power data to calculate thermalcharacteristics for the cables (step 32). The thermal characteristicsmay include, for example, thermal rise, maximum power, and overallend-to-end cable health. If a thermal rise at one of the cables exceedsa specified threshold (step 33), the thermal modeling module 18 may takeaction to reduce the risk of unsafe operation at the cable (step 34).This may include, for example, identifying the cable in a riskassessment table, graphical image, alert, alarm, message, or otherindication presented to a user, or preventing operation of the portconnected to the cable. The thermal modeling module 18 may, for example,generate a table or image to indicate cable health for a selected powerlevel and environment for a cable or bundle of cables, as well asgenerate alarm states (e.g., lights) and messages (e.g., syslog). Thethermal rise may refer to a specific temperature, delta temperature,change in temperature (e.g., percent or increase above a baselinetemperature), or a rise in temperature over a period of time.

FIG. 3B is a flowchart illustrating details for cable safety monitoringin accordance with one embodiment. Real-time electrical data including,for example, voltage and current at the PSE, PD or both PSE and PD, andimpedance are measured for the cable (e.g., each wire, each wire pair,each phase) at step 35. Cable characteristics (e.g., cable routing,length, stretch, gauge, bundle adjacencies) are identified (step 36).Thermal characteristics and wire variations (e.g., stretch (thinning))are calculated (step 37). If the cable does not meet a specified safetythreshold (e.g., a thermal rise or stretch at one of the cables exceedsa specified limit) (step 38), the cable modeling module 18 may takeaction to reduce the risk of unsafe operation at the cable (step 39). Aspreviously described this may include, for example, reducing poweroutput at the PSE or generating a notification or alarm (e.g.,illuminate LED at PSE, transmit system warning).

It is to be understood that the processes shown in FIGS. 3A and 3B, anddescribed above are only examples and that steps may be added, removed,or combined, without departing from the scope of the embodiments.

The following provides examples for determining wire gauge, bundle size,and cable adjacencies, and presenting safety data and thermal modelingresults to a user.

In one or more embodiments, wire gauge calculations may be made usingV_out (voltage at port of PSE), V_in (voltage at PD), I_individual_cable(current of cable), and TDR_m (cable length). In one example,calculations are performed assuming no connector loss. The resistancecalculations may be performed as follows:R_individual conductor=(V_out−V_in)/I_individual conductor; andR_mOhm/m=(R_individual_conductor/TDR_m)×1000.R_mOhm/m may be used to determine the AWG for the conductor.

The user may enter the basic wire gauge for the assessment calculationsif there is not an intelligent PD to provide V_in.

FIG. 4 illustrates an example of a PSE 40 that may be used to providemeasurements for use in automatically calculating cable adjacency. Inthe example shown in FIG. 4, the PSE 40 includes two PHY (circuitry forphysical layer functions) each having a SerDes 41(Serializer/Deserializer), a signal receiver 44, and a signal generator46. The PSE 40 may comprise any number of ports and correspondingcomponents. In one embodiment, a 1 MHz (or any other frequency) pulse istransmitted by the signal generator 46. The pulse is used toautomatically determine cable to cable proximity by calculating ameasured field strength (E Field 48) at the receiver 44. The pulse maybe used to track a cable tied to a particular port or switch within acable bundle referenced to the transmitting port. The pulse may be used,for example within a switch or router during bring up. The 1 MHz pulsecannot be used to determine cable proximity between switches in anetwork or in a situation wherein a data center is running productiontraffic and a new switch or new cable plant is added. In this case, apacket pulse generator may be used as shown in FIG. 5.

FIG. 5 illustrates a plurality of PSEs 50 a, 50 b, 50 c, 50 d, 50 e,with one or more PSEs configured as a packet pulse generator for use inautomatically calculating cable adjacency and bundle size determination,in accordance with one embodiment. The PSE includes a SerDes 51, signalreceiver 54 and signal generator 56, as previously described. The PSEsmay communicate with one another over an Ethernet command portcommunications plane or over a data plane, for example. The packet pulsegenerator is a specific packet type (packet 55 in FIG. 5) transmittedinstead of idle packets and with a higher energy content achieved byincreasing the transmitted signal. The packet 55 is detected and thereceiver 54 calculates the cable to cable distance based on the fieldstrength (E Field 58). In the example shown in FIG. 5, PSE 50 bgenerates the packet 55 and the field strength 58 is measured by PSE 50a. The packet pulse generator allows the equipment and cable plant tochange over time with constant (or periodic) updates to thecable-to-cable adjacency within the data center or office environment.

In one embodiment, the packet pulse generator carries switch IP(Internet Protocol) address and port ID (identifier) so that adjacentswitches in the data center can identify where the packet is sourcedfrom and return the received calculation for each port on the switchreceiving or recognizing the packet. In one example, the packet 55includes the source equipment IP address (e.g., IP address for Ethernetconsole port or command control panel), source equipment definition(e.g., what kind of switching or routing equipment), source port (e.g.,port number, port power capability, port speed capability), signal datadefinition (e.g., data packet type (FFFF0000, FF00, AA55, etc.)), anddata (e.g., as many bytes as possible of the signal data definition).

The pulsing and high frequency tests described above may be used todetect cable architecture (e.g., cable bundling, cable adjacency, bundlesize) and basic dielectric calculations may be used to determine cableinsulation type. In one example for a 96 port switch, a source wirepulse may be transmitted on one port and the pulse field strengthmeasured on 95 ports. This process may be repeated through 96 ports or afewer number of ports. In another example, a pulse may be sent on only aportion of the ports until an arrangement of the cables is identified.The cable bundling may be determined by using field strengthmeasurements to determine cable location and cable adjacency. Forexample, finite element analysis and a convergence algorithm may be usedto determine cable-to-cable proximity. In order to detect shielded foil,the pulse strength may be increased on a closest pair to determine if achange indicates shielded or not shielded. The measured field strengthwill increase with a smaller factor with a shielded cable. An algorithmoutput may be used to determine the proximity of cables and build atable.

As described below, the SerDes 51 at the PSE may also be used totransmit a high frequency signal, which is measured by the receiver todetect stretch of the wire over time. Also, cable adjacency may bedetected through monitoring cross-talk in a pulse power system, asdescribed below.

It is to be understood that the methods and systems described above fordetermining cable adjacency and bundle characteristics are only examplesand that other devices or methods may be used without departing from thescope of the embodiments. Also, if bundle characteristics are known,this information may be manually input to the thermal modeling system.In one or more embodiments, both the 1 MHz pulse and packet pulsegenerator may be used to determine cable adjacencies. For example, the 1MHz pulse may be used during bring up and the packet pulse generatorused for periodic updates.

FIG. 6A illustrates an embodiment that may be used to determine cablelength and health. In the example shown in FIG. 6A, PSE 60 includes aSerDes 61, signal receiver 64, TDR (Time Domain Reflectometer) 65, andsignal generator 66. The TDR 65 may be used to determine the cablelength for any port, which may be used to calculate wire gauge (e.g.,AWG). If the voltage at the PD 12 is known by the PSE 60, this may beused in conjunction with cable length to determine cable AWG per port,as previously described. The TDR 65 may also be used to evaluate anddetermine the cable segments and connection quality. When the PHYdetects a cable is connected, a TDR process may be performed todetermine the basic cable layout. TDR data may provide, for example,cable length and maximum loss, number of cable segments (length of cablesegments and loss per segment, connector count and loss), andidentification of cable anomalies. During a TDR process, a cable healthassessment may be performed based on losses in the cable. The healthassessment may determine the relative loss at each segment (conductor ina particular length of cable) and at each segment point (e.g., RJ45connector or other type of connector). Using the defined wire gaugecalculations, each cable segment in the entire cable length may beevaluated for maximum conductor current. Each connector may be evaluatedfor its ability to handle the port conductor current. The healthassessment along with overall wire gauge calculations may be used todetermine the maximum conductor current of an end-to-end cable. In oneembodiment, transmit and receive equalization sequences or channeloperating margin may be used in place of TDR.

FIGS. 6B and 6C illustrate examples for identifying wire stretch, inaccordance with one or more embodiments. The vertical cable section 14 a(shown in FIG. 1B) may comprise a cable bundle comprising any number ofcopper wires and one or more tie points along the length of the cable.The weight of the cable bundle may begin to stretch the copper wires 21within the bundle over time. As shown in the exploded schematic view ofthe wire 21 in FIG. 1B, the wire may have one or more areas that becomethinner over time (diameter D2) from physical strain.

In one example, the TDR 65 (FIG. 6A) may be used to identify impedancechanges over time, as shown in the graph 67 of impedance over distancein FIG. 6B. Impedance is shown over the length of the wire at Time 1,Time 2, Time 3, and Time 4. These variations indicate changes inimpedance due to changes in the copper wire 21. Tracking changes overtime (e.g., month to month) will show the growing strain on the wires.In one or more embodiments, these changes are monitored and when athreshold level is reached, a notification (e.g., alarm is generated).For example, an impedance change≤10% may indicate a safe condition. Achange in impedance of between 10% and 20% may indicate a possiblesafety condition. A change in impedance of more than 20% may indicate asafety condition.

In another embodiment, high frequency loss may be used to identify acritical stretch condition. In one example high frequency loss ismeasured at a receiver over time. As shown in FIG. 6C, a transmitter(e.g., SerDes transmitter at the PSE) couples high frequency noise at 69a. A powered device at the other end of the cable 68 has a receiver(e.g., SerDes receiver) that measures the high frequency signal at 69 b.The receiver measures amplitude over time. The stretch point of the wirewill result in a high frequency impedance that grows over time. Areceiver equalizer may be used to monitor the loss over time. Anotification or alarm as described above may be used to indicate asafety condition.

The monitoring of the stretch as described herein may be used alone orin combination with the thermal modeling to provide an additional layerof safety monitoring or health indication of the cable.

As shown in FIGS. 7, 8, 9, and 12 tables 70, 80, 90, and 120 may becreated from automatically generated data, manually entered data, andcalculations. The table 70 shown in FIG. 7 is based on smart PDs, whichare configured to measure their input port voltage. The table 80 shownin FIG. 8 is based on a Vpd calculated by the PSE. The tables 90 and 120shown in FIGS. 9 and 12, respectively, are based on smart PDs andautomatically gathered cable bundle information.

Referring first to FIG. 7, for each port at the PSE 10 (e.g., 1-24), thetable 70 includes Vpse (V_out), Iport (I_individual_cable), Pport(power_port), Vpd (V_in), TDR (length), Cable AWG (wire gauge), CableTemp Rating, Bundle (bundle containing cable (e.g., A, B)), Pcable(calculated power dissipated by (or in) the cable), Thermal Rise, andCable Thermal Status. The PSE 10 measures Iport, Vpse, Pport, and TDR(to determine cable length) (FIGS. 1 and 7). The PSE 10 measures thereal-time current in the cable and the real-time output voltage at thePSE. In one or more embodiments, the PD 12 measures its port voltage andsends it to the PSE 10 via Layer 2. The user may input the cabletemperature rating for each AWG, and the bundle in which the cable islocated. This information may be input at the GUI 11 at the networkoperations center device 19, for example, and stored at the thermalmodeling module 18. The thermal modeling module 18 (at PSE 10 or networkdevice 19) calculates Pcable based on a combination of Iport and Vpd.The thermal rise may be calculated based on Iport and bundle size. Thethermal rise calculations may take into account, for example, cablecharacteristics (e.g., gauge, area, length, material, insulation type),location (e.g., cable adjacency, bundle location, bundle size),electrical characteristics (e.g., current, voltage, resistance, power),thermal properties (e.g., conductive and convective properties of cable,environment (air gaps, bundling contact, maximum expected ambienttemperature at location of cable routing)), or any combination of theseor other variables.

The cable thermal status is based on the calculated thermal rise andmaximum temperature rating of the cable and may be represented, forexample, as a color (e.g., green (safe operating condition), yellow(approaching unsafe operating condition), red (unsafe operatingcondition)) based on a specified limit or threshold. The threshold maybe based on standard temperature limits for the cable or may be userdefined. Cable health may be determined based on an expected Pcablebased on Iport, Vport, and TDR as compared to Pcable calculated usingVpd.

Referring now to FIG. 8, the table 80 shows an example of a riskassessment table for a system in which the PDs are not configured tomeasure port voltage and provide Vpd. The Vpd column in table 80 ismoved from the automatically gathered data (in table 70) to thecalculated data. As previously described, the PSE 10 measures Iport,Vport, Pport, and TDR (to measure cable length). A user may input AWG ofcable conductors, the cable temperature rating, and the bundlecontaining the cable. The thermal modeling module 18 (at PSE or othernetwork device 19) may calculate: Vpd based on Iport, Vport, cablelength, and AWG; Pcable based on combination of Iport and Vpd; andthermal rise based on Iport and bundle size. The cable thermal status isbased on thermal rise and may be indicated as green, yellow, or red, asdescribed above. The cable health cannot be determined without the helpof the PD.

The table 90 in FIG. 9 illustrates an automated case in which the smartPDs provide the port voltage (Vpd) and the PSE uses a signal or packetpulse (as described above with respect to FIGS. 4 and 5) toautomatically determine cable bundle configuration. In this example,data including Vpse, Iport, Pport, Vpd, TDR, Cable AWG, and Bundleinformation is automatically gathered. The cable power (Pcable) andresulting thermal rise are calculated. As previously described, a cablethermal status column is provided to indicate the health of the cablebased on thermal rise thresholds.

FIG. 12 is an example of a risk assessment table 120 for use with higherpower operation (e.g., ESP), in accordance with one embodiment. Thetable includes the same parameters shown and described above withrespect to table 90 of FIG. 9, with higher voltage and power levels.

It is to be understood that the tables 70, 80, 90, and 120 shown inFIGS. 7, 8, 9, and 12, respectively, are only examples and thatdifferent columns or data may be included or different formats usedwithout departing from the scope of the embodiments. Also, as describedabove, different data may be automatically gathered or calculated basedon system configuration or capability of the devices. In one or moreembodiments, the table may also include a column identifying an increasein stretch in the wires, as described above.

FIG. 10 illustrates an example of a customer risk assessment graphicalimage 100. In this example, an indication is provided for each cablewith respect to the risk/health assessment table. As shown in FIG. 10,one cable is identified as “Health: Good, 22 AGW, P_c=2.3 W, Trise=6 degC.” and another cable is identified as “Health: max current exceeded, 24AGW, P_c=10.2 W, Trise=12 deg C.”. The graphical view 100 shown in FIG.10 may be available on a customer screen (e.g., GUI 11 at networkoperations center device 19 in FIG. 1A) or on an equipment displayscreen.

It is to be understood that the tables 70, 80, 90, 120 shown in FIGS. 7,8, 9, and 12 and the graphical image 100 shown in FIG. 10 are onlyexamples and that different data, more or less data, or any combinationor presentation of data may be provided in the tables or shown in thegraphical view. A GUI may allow a user to select how much information ordetails are presented and how they are presented (e.g., table, image).Also, the user may select to view only a portion of a cable plant, oneor more cable plants, or only cables or cable plants with thermal orpower issues.

In addition to (or in place of) the table 70, 80, 90, 120 or schematic100, the thermal modeling module 18 may transmit one or more alerts(alarm, message, syslog, etc.) when a specified threshold has beenreached (e.g., thermal rise above a specified limit, maximum current orpower exceeded in one or more cables, stretch limit exceeded). Forexample, the thermal modeling module 18 may determine or user inputprovided to define appropriate thresholds for allowable temperature risein a cable for safe operation per port. In one example, a red cablethermal status may prevent the port from operating and a yellow cablethermal status may only allow the port to operate with userintervention. In one embodiment, the GUI may allow for a red override.The user may set the green/yellow/red threshold as appropriate for theircable plant configuration. In one embodiment, the thermal modelingmodule 18 may generate a flag based on worst case PD classificationcurrent. The alarm conditions may include, for example, a strict mode inwhich the PSE 10 monitors real-time PD currents and enforces a currentlimit (i.e., shuts down port when current limit is exceeded), and anon-strict mode in which the PSE monitors real-time PD currents andgenerates an alarm when a current limit is exceeded. The alarm andassessment information may be displayed, for example, on a systemdisplay panel or customer interface and provide an indication thatattention is needed (e.g., blue attention LED (Light Emitting Diode),syslog message sent through the Ethernet control interface port to thenetwork operations center).

As previously described, in one or more embodiments, the power maycomprise high voltage pulse power or high voltage multi-phase pulsepower. FIG. 11 illustrates a simplified example of voltage and currentin a two-phase pulse power system. The voltage for phase A is shown at112 a and the voltage for phase B is shown at 112 b. The continuousphase current is shown at 114. The voltage is switched between a pulseon-time (e.g., voltage>24 VDC, voltage≥60 VDC, voltage≅380) and a pulseoff-time (e.g., voltage<12V, ≥24V). It is to be understood that thevoltages and currents shows in FIG. 11 illustrate a simplified examplewith idealized waveforms. As previously noted, the voltage duringoff-time may be greater than zero for use in fault detection. Forexample, the voltage during pulse-off time may comprise a low voltage toprovide for fault sensing during pulse-off time. Also, the voltagepulse-on times may overlap between phases so that at least one wire ison at any time. During phase overlap in the multi-phase systems, thetotal cable current is shared across all ON wires. When the phases arecombined at the PD, the result is continuous DC voltage as shown by thephase current 114. As described in U.S. patent application Ser. No.16/380,954, referenced above, the multi-phase system may comprise anynumber of phases, with any phase offset or overlap.

In one or more embodiments, pulse power is monitored using thetransition edges 113 of one pair and cross-talk is monitored on anotherpair. A level of identified cross-talk intensity may be used todetermine the proximity to the pulse power line in transition. This maybe used to determine bundling calculations and effective distancesdescribed above. The pulses may also be used for TDR measurements.

In one or more embodiments, a cross-talk profile may be used to filterout unintentional noise from a portion of the circuit identifying aload. For example, cross-talk may be measured on each line and filteredout from a pulse-off time determination circuit. In a tightly packedbundle, this may be used to prevent accidental shutdown due to aliencable cross-talk.

As can be observed from the foregoing, the embodiments described hereinmay provide many advantages. For example, one or more embodiments may beused to prevent the unwanted heating of cables (e.g., individual cables,bundle of cables) in communications cables where power is delivered overthe cables to a powered device. The calculations may be done atinstallation and continued in real-time during idle packet transfer ofthe communications circuit, for example. Alarm conditions, attentionlights, LCD (Liquid Crystal Display), and messaging may be used to alertthe end user in the event an unwanted amount of power beyond the abilityof the cable and cable environment is requested by the PD. In one ormore embodiments, the PSE port may automatically limit the poweravailable for delivery based on the ability of the cable to safelydeliver the required current, and thereby prevent serious damage to thecable plant, building, or user. The embodiments may be used, forexample, by network engineers who manage networks with a significantdeployment of PoE, PoF, or ESP powered devices to provide a warning ofdeployment scenarios where the self-heating of cables could jeopardizethe data integrity of the cables. The system may be used for long termplanning in a cable plant, for example. One or more embodiments allow anetwork engineer to simply review the cable plant health assessment,which provides a more accurate assessment than may be provided withvisual inspection and also saves a significant amount of time.

Although the method and apparatus have been described in accordance withthe embodiments shown, one of ordinary skill in the art will readilyrecognize that there could be variations made to the embodiments withoutdeparting from the scope of the invention. Accordingly, it is intendedthat all matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense.

What is claimed is:
 1. A method comprising: monitoring real-timeelectrical data for Power Sourcing Equipment (PSE) transmitting powerover a cable to a Powered Device (PD); and identifying changes in thereal-time electrical data indicating strain on one or more wires in thecable due to stretching in said one or more wires; wherein saidstretching comprises a localized reduction in diameter of said one ormore wires along a vertical portion of the cable.
 2. The method of claim1 further comprising using a time domain reflectometer to identifyvariations in impedance over a length of the cable to indicate saidstretching in said one or more wires.
 3. The method of claim 1 furthercomprising using said real-time electrical data to calculate thermalcharacteristics for the cable and periodically updating the thermalcharacteristics based on the monitored data.
 4. The method of claim 1wherein the power comprises multi-phase pulse power and the monitoreddata comprises voltage and current for each phase.
 5. The method ofclaim 1 further comprising identifying a wire gauge of the cable basedon the data.
 6. The method of claim 1 further comprising measuring cablelength using a time domain reflectometer, wherein the cable length isused to calculate a wire gauge.
 7. The method of claim 1 furthercomprising measuring a high frequency signal at a receiver at the PD toindicate said stretching.
 8. The method of claim 1 further comprisingidentifying a percentage of stretch over a specified threshold level andsending a notification.
 9. A method comprising: monitoring real-timeelectrical data for Power Sourcing Equipment (PSE) transmitting powerover a cable to a Powered Device (PD); identifying changes in thereal-time electrical data indicating strain on one or more wires in thecable due to stretching in said one or more wires; and detecting anadjacent cable by measuring cross-talk between wires in the cables. 10.The method of claim 9 wherein the power comprises pulse power andwherein cross-talk is measured during a transition of a pulse of thepulse power.
 11. The method of claim 9 further comprising measuringcable length using a time domain reflectometer, wherein the cable lengthis used to calculate a wire gauge.
 12. The method of claim 9 furthercomprising measuring a high frequency signal at a receiver at the PD toindicate said stretching.
 13. A method comprising: monitoring real-timeelectrical data for Power Sourcing Equipment (PSE) transmitting powerover a cable to a Powered Device (PD); identifying changes in thereal-time electrical data indicating strain on one or more wires in thecable due to stretching in said one or more wires; and identifying athermal rise at the cable and limiting power output at a port of the PSEconnected to the cable.
 14. The method of claim 13 wherein saidstretching comprises a localized reduction in diameter of said one ormore wires along a vertical portion of the cable.
 15. The method ofclaim 13 further comprising measuring a high frequency signal at areceiver at the PD to indicate said stretching.
 16. The method of claim13 further comprising identifying a percentage of stretch over aspecified threshold level and sending a notification.
 17. The method ofclaim 13 further comprising detecting an adjacent cable by measuringcross-talk between wires in the cables.
 18. A method comprising:monitoring real-time electrical data for Power Sourcing Equipment (PSE)transmitting power over a cable to a Powered Device (PD); identifyingchanges in the real-time electrical data indicating strain on one ormore wires in the cable due to stretching in said one or more wires; andidentifying a percentage of stretch over a specified threshold level andlimiting power output at a port of the PSE connected to the cable. 19.The method of claim 18 further comprising monitoring said strain on saidone or more wires and identifying a cable health based on changes insaid monitored strain and thermal characteristics.
 20. The method ofclaim 18 further comprising identifying an adjacent cable andcalculating a thermal rise on the cable based at least in part on saididentified adjacent cable.